Heat loss responses at rest and during exercise in pregnancy: A scoping review.

BACKGROUND: The teratogenic risk associated with maternal hyperthermia (i.e., core temperature ≥39.0 °C) has been a crucial motive in understanding thermoregulatory responses in pregnancy. To date, a substantial number of studies have focused on core temperature responses in a wide range of exercise intensities, duration, and ambient temperatures. Fortunately, none have reported core temperatures exceeding 39.0 °C. Nonetheless, there are limited studies that have provided substantial insight into both dry and evaporative heat loss mechanisms involved in facilitating the maintenance of core temperature (≥39.0 °C) during heat stress in pregnant women. The purpose of this scoping review was to summarize the available literature that has assessed heat loss responses in studies of human pregnancy. METHODS: A search strategy was developed combining the terms pregnancy, thermoregulation, and adaptation. A systematic search was performed in the following databases: PubMed, Embase, Scopus, and ProQuest. Studies eligible for inclusion included pregnant women between the ages of 18-40 years old, and at least one measurement of the following: sweating, blood flow, skin temperature, and behavioural responses. Retrieved data were categorized as evaporative (sweating), dry or behavioural heat loss responses and summarized narratively. RESULTS: Thirty-three studies were included in this review (twenty-nine measured physiological responses and four measured behavioural responses). Studies suggest that during exercise, evaporative (sweating) and dry (skin blood flow and temperature) heat loss responses increase from early to late pregnancy in addition to greater cardiac output, blood volume and reduced vascular resistance. Behavioural practices related to heat loss responses are also influenced by cultural/religious expectations, personal preferences and sociodemographics. CONCLUSION: The findings from this review suggest that pregnancy modifies evaporative (sweating), dry and behavioural heat loss. However, future studies have an opportunity to compare heat loss measurements accounting for gestational weight gain and thermal sensation/comfort scale to associate physiological responses with perceptual responses across pregnancy.

How Many Valid Days Are Necessary to Assess Physical Activity Data From Accelerometry During Pregnancy?

BACKGROUND: The authors examined whether or not ≤3 days wearing Actical® accelerometers provided acceptable results in comparison with the recommendation of ≥4 days in women across gestation. METHODS: A total of 26, 76, and 57 participants at early, mid, and late pregnancy, respectively, were assessed. Participants were instructed to wear the device for 7 days and women who wore it for ≥4 days were included. For each participant, 3, 2, and 1 day(s) were randomly selected. Paired comparisons, intraclass correlations coefficients, and kappa statistics were performed for ≥4 days (criterion) versus 3, 2, and 1 day(s). Averages (in minutes per day) of sedentary time, light, moderate, vigorous, moderate to vigorous physical activity (PA) and steps per day were examined. RESULTS: When 3 valid days were compared with the criterion, no significant differences were found for any gestational period. The intraclass correlations coefficients were "high" for all PA-related variables. The k values varied from .819 to .838 across pregnancy ("strong"). Two and 1 valid day(s) versus the criterion showed significant differences in some PA intensities, reduced intraclass correlations coefficients, "moderate" k values for 2 valid days (.638-.788) and "minimal-to-moderate" k values for 1 valid day (.367-.755). CONCLUSION: In pregnant women during early, mid, and late pregnancy, PA data obtained from 3 valid days of wear was equivalent and agreed with ≥4 valid days.

Exploring Beliefs About Exercise Among Pregnant Women in Rural Communities.

INTRODUCTION: Women who are pregnant in rural communities are disproportionally impacted by obesity and sedentary behavior, and this could be related to having negative beliefs about exercise during pregnancy, leading to inactivity. The purpose of this study was to identify self-reported beliefs about exercise among pregnant women in a rural community. METHODS: Pregnant participants (N = 70) between 8 and 16 weeks' gestation were recruited from an obstetric clinic serving a rural population. An open-ended questionnaire addressing beliefs about exercise and based on the constructs of the theory of planned behavior was administered. Descriptive survey results were analyzed by calculating means and frequencies. Open-ended responses were assessed by inductive content analysis. RESULTS: Commonly reported advantages of exercise during pregnancy included improved perinatal health outcomes and weight management. Commonly reported disadvantages included an increase in fatigue and concerns for maternal and fetal safety. Common facilitators of exercise included access to resources, free time or a decrease in demands from work, and support systems including family and friends. Common barriers to exercise included a lack of time, physical changes including feelings of nausea and fatigue, and lack of access to resources. DISCUSSION: This study was the first to report beliefs about exercise during pregnancy in a rural setting. Responses in the current study suggest potential gaps in knowledge of evidence-based information regarding physical activity during pregnancy. Beliefs as well as reported barriers and facilitators of physical activity during pregnancy were similar those reported in other populations. In addition, access to resources (or lack of) appears to be an important facilitator (or barrier) among women in rural settings; thus, developing strategies designed to overcome this barrier, specifically in rural areas, is critically important. Future intervention strategies need to be tailored specifically to the needs of women living in rural areas.